Question 1160367

A lawyer invested a certain amount of money in a restaurant business, expecting the earnings to be 9% per year. He invested thrice the amount in a retail business, expecting the earnings to be 11% per year. If after a year, the total interest from the investment is 63,000, how much did he invest in the restaurant business?
<pre>Let amount invested in the restaurant business be R 
Then amount invested in the retail business, is 3R
We then get: .09R + .11(3R) = 63,000
.09R + .33R = 63,000
.42R = 63,000
Amount invested in the restaurant business, or {{{highlight_green(matrix(1,5, R, "=", "63,000"/.42, "=", "$150,000"))}}}